The invention presented in detail herein is set forth with respect to an aircraft braking system and, more specifically, to the anti-skid control portion of such a braking system. The invention, however, contemplates adaptation to a broad range of controls in which field programmable gate arrays may be employed for purposes which will become apparent herein.
In the prior art of control systems, and particularly those for aircraft brakes, the control system was devised of circuitry comprising discrete components. Over a course of time, such aircraft brake control systems evolved to the implementation of dedicated microprocessors or electronic chips, such that the control system design was primarily software controlled and algorithm dependent. The market for electronic chips has been substantially consumer driven, with little thought to after-market support. Accordingly, the expected life for many electronic systems is on the order of five years. New high density, high speed components are expected to have operational lives on the order of about seven years. While this is happening “MIL-spec” parts are being removed from production. But, airframe manufacturers expect the avionics of the aircraft to last and be supported for the life of the aircraft—often on the order of thirty years or more.
Current market trends exacerbate the problem of obsolete parts. The avionics industry, and others as well, are thus driven to change the way they do business. While consideration may be given to life-time buys (purchasing and maintaining an adequate quantity of electronics parts to service the aircraft from the beginning), such an approach is both expensive and risky. Similarly, periodic redesigns to obtain the same functionality are costly and time consuming. A better approach is to embrace a new technology that is flexible and has a long period of projected availability.
Field Programmable Gate Arrays (FPGA), though not previously applied to control systems in general or braking systems in particular, have been found to be attractive to fit the avionics needs of the aircraft industry. It is presently anticipated that FPGA's are projected to be available for a long period of time. They are cost effective, they are both scalable and flexible in application, they involve a low to moderate risk factor, and they serve to reduce dependency on microprocessors that are given to obsolescence.